The overall goal of this proposal is to examine the molecular basis for the development of hyperandrogenic states and consequent impairment of follicular function. Ovarian hyperandrogenism leads to ovulatory dysfunction including anovulation and infertility. In some cases such as polycystic ovarian syndrome, hyperandrogenism usually accompanies increased insulin resistance resulting in elevated insulin levels, and increased IGF-1 system. The altered endocrine and paracrine milieu results in increased androgen production by theca-interstitial cells, ovarian hyperplasia and loss of ovulatory capacity of the follicles. The objective of this proposal is to examine the cellular mechanisms responsible for hyperandrogenism and the resultant effects of excess androgen exposure on follicular function. To accomplish this, three specific aims are proposed. Aim 1 will examine the role of increased cholesterol transport into theca-interstitial cells in response to insulin, IGF-1 and LH. This will be tested by examining the induction of HDL and LDL receptor expression in rat theca-interstitial cells by in situ hypbridization and by Northern blot analysis, and by determining the uptake and utilization of cholesterol for androgen synthesis. Aim 2 will examine the cellular mechanism involved in the deleterious effects of androgen exposure on the ovarian follicular function in response to insulin/IGF-1 and FSH. This will be examined by analyzing changes in cell cycle constituents involved in the progression of restriction points in cell cycle, namely cyclins and cyclin-dependent kinases in response to insul/IGF-1 and FSH in androgen exposed follicles. Aim 3 will examine the effect of androgen exposure on the follicular function. This will be determined by examining the signaling of insulin/IGF-1 and FSH in androgen-exposed follicles. The above studies will be carried out in rat and human tissues. The proposed studies address novel questions central to reproductive endocrinology and are directly relevant to the disorders affecting fertility.